would it be allowed if I used an application like autohotkey to map the arrow keys to WASD for a run?

Assuming the remapping rules for Undertale also apply here, then this is what the UT rules state for remapping arrow keys to WASD and remapping in general with QWERTY keyboards (not sure about others):

"You can only bind up to W, left to A, down to S, and right to D. You are allowed to use the arrow keys in addition to WASD."

The deltarune rules state "Rebinding multiple keys to a single key or rebinding keys such as to have more keys than normal for the game's functions is not allowed." other than that you should be fine

thanks guys